Photographic film.



No. 645,209; Patented Mar. la, |900.

.0. MUH.

PHO'TOGRAPHIC FILM.

. (Application led Dev. 8, 1898.) (No Model.)

Fig.

TN: aims PETERS ce Mofo-ums.. wAsumsToN, D. cA

man.

PATENT oswALD MoH, or GRLITZ, GERMANY.

PHOTOGRAPHIC FILIVI.

SPECIFICATION forming part of Letters Patent No. 645,209, dated lVIarc'h13, 190.

Application filed December 3. 1898. Serial No. 698,206'. (No specimens.)

To all whom, t may concern:

Be it known that I, OsWALD MoH, a subject of the King of Prussia, GermanEmperor, residing at Grlitz, in the Kingdom of Prussia, Germany, haveinvented certain new and useful Improvements in Processes for MakingPhotographic Films, (for which I have applied for a patentin Germany,dated September 19, 1898,) of which the following is a specification.

This invention relates to the production of flexible films which afterexposure, development, fixing, and Washing are adapted to be separatedfrom a backing-sheet which supports them during the above operation, thefilm thus separated being better adapted for printing. The manipulationof such films has heretofore been attended with difficulties, so thatthey could not be used toy advantage without considerable practiceeither by professional operators or amateurs.

The object of the present invention is to remove the objectionablefeatures hitherto existent in that the films prepared by the new processdry easily and can be drawn off with certainty, and at the same timefurther improvements are made with a view to retouching as well asreinforcement and protection to the film.

In the accompanying drawings, Figure 1 is a sectional View of a fiexiblefilm formed according to my invention. Fig. 2 shows two such filmsplaced together for the purpose hereinafter set forth.

Referring to Fig. 1, the process is carried out as follows: The papersheet D, which is to serve as a support, first receives a coating A ofcaoutchouc. Then this coating is covered with a layer B of collodion,and, finally, the gelatin layer C, which serves to hold the silver saltis applied. The light sensitive film is thus composed of the followingthree layers: first, the caoutchouc layer resting direct on the paper;second, a collodion layer intimately bound to the caoutchouc layer;third, an upper gelatin layer serving as carrier for the silver salt. Inthe drawing off of the complete films it is of the greatest importancethat, contrary to the arrangements previously used, the caoutchouc layershould rest directly on the paper. In the first place after the negativefilm prepared by the' abovedescribed process is exposed, developed, xed,and washed it presents after drying the advantageous peculiarity that itcan be stripped with ease and certainty from the paper. The caoutchouclayer adheres to the paper fibers sufficiently to enable the differentoperations of developing, washing, dac., to be effected, but'notsufficiently to present any consid erable resistance to the stripping ofthe dry film from the paper. Thus a clean easy sepas ration of the film'from the paper is attained. A further advantage consists therein thatthe caoutchouc layer resting directly on the paper takes the grainthereof. By this means it is possible to give to this caoutchouc layerby selection of the proper paper a grain of any desired coarseness. Thisgrain can be utilized to take the place of the retouching of thefinished film, in whole or in part, in that the light-rays are dispersedand divided by the said grain. The minor irregularities of the negativeare thus rendered ineffective by the dispersion of the light by thegrain of the film without losing any of the characteristic features ofthe picture. These films with different grains thus oer a substitute forthe tedious and troublesome work of retouching of the negative, andthere are thus obtained with a little supplementary work, which initself is materially facilitated by the grain, results' that correspondto the technical requirements of photography, which were heretofore onlyattainable by very difficult and tedious work.

The negative film is somewhat thin and easily creased,which isobjectionable in printing. To avoid this, the film is strengthenedthatis, made thicker-as has hitherto been customary. For this purpose,however, there is used in this case a gelatin paper (see Fig. 2) whichlhas similar layers E F G H to the layers of the light sensitive film,with the eX- ception that the gelatin layer thereof contains no silversalt. This paper is wetted in Water and pressed against the originalnegative while the latter is still on the paper, so that the two gelatincoatings adhere to one another. By rolls or other suitable means the twofilms are closely pressed together and the product thus obtained is hungup to dry. Y After the drying the two sheets of paper inclos- IOO ingthe negative can easily be stripped 0E, leaving a strong thicknon-curling smooth sheet which can be copied from either side.

Substantial advantages of the method of revinforcement are, first, theease and convenience of the operation for the operator, since thegelatin layers do not have to be carefully applied, with considerableloss of time; but the coated papers are simply squeezed together, andafter drawing away the support` ing-paper a Iilm is always obtained ofuniform thickness and quality; second, the iilm is completely protectedfrom dust and other soiling substances by the superimposed papel' sheetsduring the drying. Finally, as both gelatin layers are placed on thepaper supports with identical intermediate layers the expansion iuwetting and the contraction in drying are completely uniform, and thedried picture is thus completely even.

I claim- A process for producing light sensitive films, Y

